In printers of various types such as, for example, serial dot-matrix printers, a printing head acts on a sheet of paper which bears on a platen typically constituted by a roller. The sheet of paper is held tightly against the platen in the vicinity of a printing line by means of a suitable pressure device. This prevents the sheet of paper from vibrating, ensuring good print quality and a low noise level; the pressure device also facilitates the movement of the sheet of paper towards the printing line.
A known pressure device is constituted by a support plate which is anchored to a frame of the printer. A flexible plate is glued to the support plate, generally by means of a two-part adhesive. A free end of the flexible plate, which extends substantially along the entire printing line, is pressed against the platen to keep the sheet of paper fitting tightly.
A disadvantage of these pressure devices is that the method of producing them is quite complex. In particular, the support plate has to be degreased and cleaned with suitable solvents beforehand and then completely dried; moreover, the gluing of the flexible plate requires operations which cannot be automated and which have to be performed manually. The method is therefore extremely slow and expensive and this is reflected in the final cost of the pressure device and hence also of the printer as a whole.
Moreover, the use of glues and solvents makes the method of producing the pressure device highly polluting.
Known pressure devices also have durability problems, since the fairly large forces which act on the flexible plate in a condition of use may cause the flexible plate to be detached from the support plate.